In modern quartz controlled watches employing a stepping motor and time indicating hands there is occasionally a tendency for external forces arising from movements of the wearer to be transmitted back through the gear train and to react unfavourably on the behaviour and performance of the stepping motor. To avoid this unfavourable reaction various solutions may be proposed; among others there has been suggested the use of mutilated gears taking various forms, or pawl and ratchet mechanisms. Mutilated gears, depending on their form, may present certain problems of manufacture as well as matching thereof to provide a smooth transmission of rotational motion. The use of pawl and ratchet mechanisms takes up space and also abstracts energy from the motor. The present invention provides a solution to the problem which utilizes gears having readily formed teeth, even although such teeth are asymmetric. Through the employment of an idler gear similar to a drive gear, but representing a reflection about a diameter of said drive gear, it has been found that transmission from the stepping motor to the rest of the mechanism may take place only in one direction and only in one sense of rotation. Thus, shocks applied to the timepiece through outside influences will not be transmitted back to the drive motor whether or not these tend to accelerate the motor or to stop it.
It is obvious that although the mechanism may find its greatest use in the timekeeping art other uses will suggest themselves to those involved with like mechanical devices.